1. Field of the Invention
The present invention relates to labeling machines and specifically to automatic labeling machines employing multiple label dispensers.
2. Description of the Prior Art
In an automatic labeling machine, labels on a roll are delivered from a label dispenser and adhered to containers automatically as the containers flow continuously past a labeling station. A problem occurs when the supply of labels is depleted in the dispenser, since the machine must then be shut down to reload a new roll of labels thus causing interruption in the labeling operation. Further, other failure conditions at the dispenser such as "Fail Safe" and "CPU Fail" render the dispenser inoperable thereby stopping the labeling operation. A second dispenser of labels mounted on the same side of the labeling machine can be provided and mounted so as to duplicate the operation of the first dispenser. This second dispenser is loaded with a supply of labels or otherwise serviced while the first dispenser is operating. When the first head becomes inoperative because it is out of labels or for other reasons, the second dispenser takes over. The reverse sequence may also occur in that the second dispenser is operative while the first dispenser is being serviced.
The need in such cases for accurate process control in such dual dispenser systems is apparent. The control complexity increases when a machine is constructed for applying two labels, one to the front and another to the back of a container simultaneously thus creating a system with four label dispensers (two for the front and two for the back) such that maximum throughput can be maintained as backup/transfer label dispensers are provided for both sides of the container.